(中国科学院 上海硅酸盐研究所, 上海 200050)
摘 要: 应用 Na|Na+βAl2O3|NaxPb1-x固体电解质电池测定了42个Na/NaxPb1-x(x =0.043~0.987 8)电池在508~648 K的电动势。计算了钠/高铅钠合金(液,x =0.043~0.6)电池电动势及其温度系数, 钠在合金中的活度系数、 偏摩尔熵 - S(Na)、 偏摩尔焓-H (Na)和x(Na)的关系。 热力学函数对钠摩尔分数的线性关系,相应于在钠 铅相图中的富铅相界、共晶体NaPb4, NaPbNaPb3和化合物NaPb组分处产生的偏折,表征液态钠铅合金存在着类似于固相结构的化学络合物。根据电池电动势对组分和温度的关系,测量了合金的熔化温度及NaPb4, NaPbNaPb3, NaPbNa9Pb4的共晶温度。
关键字: 钠β氧化铝; 固体电解质; 钠铅合金; 热力学函数
(Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai 200050, P.R.China)
Abstract:EMFs of fortytwo Na/NaxPb1-x (x=0.043 !33~0.987 8) cells were measured by using a Na|Na+ βAl2O3|NaxPb1-x solid electrolyte cell. The EMF and its temperature coefficient of the Na/NaxPb1-x (liquid), activity coefficient of the sodium in NaxPb1-x, sodium partial molar entropy - S (Na) and partial molar enthalpy -H (Na) were also calculated as a function of x (Na). For the liquid Na/NaxPb1-x cell, the linear relationship between dE/dT,- S (Na), -H (Na) and x(Na), respectively, were deflected at x(Na)= 0.083, 0.20, 0.39, 0.48, 0.52 which correspond to the rich lead phase, NaPb4 entectic point, NaPbNaPb3entictic point and NaPb compound analogous to transformation of phase region inthe NaPb system. The results indicate that chemical complex exist in the molten NaxPb1-x near the temperature of liquids line in NaPb phase diagram. The moing temperatures of NaPb alloys and entectic temperatures of NaPb4, NaPbNaPb3and NaPbNa4Pb9 have been determined from the dependence of the cell EMFon component and temperature.
Key words: sodium betaalumina; solid electrolyte; sodiumlead alloy; thermodynamic function